"Ultimately, this is about the truth and DNA is truth," Sepich said on the steps of the Supreme Court after Wednesday's arguments.

Attorneys for Maryland argued the information has helped officers solve hundreds of cold cases not related to the initial arrest.

"This is one of the most important criminal procedure cases they've had in decades because DNA is the 21st century fingerprint," says Maryland Attorney General Doug Gansler.

In court Justice Stephen Breyer compared DNA to a fingerprint calling it "no more intrusive" and "much more accurate", but Justice Sonia Sotomayor argued "there is something inherently dangerous that is not the same as fingerprinting."

The Supreme Court is expected to make a final decision before summer.

If justices rule in favor of King more than one million DNA samples in the federal database may have to be destroyed and others will never be collected.